Valve control system



Sept. 15, 1936. FlsHER 2,054,368

VALVE CONTROL SYSTEM Filed May 23, 1934 Patented Sept. 15, 1936 UNITED STATES gate-36s orrica 2,054,368 VALVE CONTROL srs'rnm Application May 23, 1934, Serial No. 727,034. 18 Claims. (Cl. 236-68) The present invention relates to the automatic control of valves, particularly such valves as are used to control the flow of fuel to a burner as, for instance, a gas valve.

In order to obtain close temperature control, it has been found desirable to move a fuel control valve to a plurality of control positions upon changes in the value of the condition being controlled instead of moving such a valve from completely closed position to completely opened position and vice versa. The average burner, however, while capable of properly burning a relatively small supply of fuel after such fuel has been initially ignited, requires a much larger flow of fuel for proper ignition. This is particularly true of gas burners wherein, if the initial supply of fuel is too small, the flame will pop back and the gas will burn in the mixer. In order to overcome this difficulty and still make it possible to 20 vary the supply of fuel to a burner, it has heretofore been proposed to arrange the control system in such manner that upon an initial demand for a relatively small amount of fuel, the valve mechanism is opened widely for a short period whereby to furnish a sufiiciently large supply of fuel for proper ignition and is then automatically operated to supply a smaller amount of fuel which is in accordance with the demand. In this manner, upon a demand for a small amount of fuel which is sufliciently large to burn properly after having been ignited but is insufiicient for the establishment of proper ignition, a large supply of fuel capable of being properly ignited is initially provided and then automatically reduced to correspond to the demand. This automatic reduction in the initial supply of fuel has heretofore been accomplished by mechanism which cooperates directly with the valve mechanism, and in some cases the arrangements have been exceedingly complicated.

An object of the present invention is the provision of an automatic control system wherein an initial large supply of fuel is provided upon a relatively smaller demand for fuel by automatically changing the adjustment or the response of the condition responsive controller each time the valve moves to or from closed position.

A further object of this invention is the provision of a valve control system wherein the condition responsive controller is electrically adjusted to give a false response to the condition being controlled whenever the valve closes and to arrange the vaive so that it can only open initially when there is a sufficient demand for fuel according to the false response of the controller to establish proper ignition. By making the condition responsive controller respond falsely when the valve is closed so as to demand a flow of fuel although in fact there is no such demand, then a relatively small actual demand for fuel will cause the condition responsive controller to demand a larger flow of fuel which is sumcient for ignition purposes. In this manner, the valve mechanism is operated to allow a relatively large supply of fuel to the burner which can be readily ignited when the actual demand is for a smaller supply. Immediately that the valve mechanism is so operated, the response of the condition responsive controller is changed again so that it responds to the actual conditions existing and, in this manner, since the actual demand is for a relatively small flow of fuel, the valve mechanism is operated to reduce the supply of fuel. This momentary relatively large opening of the valve mechanism has provided a momentary large supply of fuel which can be properly ignited.

In the specific embodiment of the invention to be hereinafter described in detail, the valve mechanism is arranged so that it can only be opened when there is a relatively large demand for fuel. The controlling thermostat is continuously subjected to an auxiliary source of heat during all times when the valve is open and the true response of the thermostat, by reason of its adjustment, is obtained when the thermostat responds to the combined action of the ambient temperature and the auxiliary heat. This auxiliary heat, however, is eliminated when the valve is closed, thereby resulting in an immediate response of the thermostat although the ambient temperature to which it responds has not changed whatsoever. As a result, a relatively smaller change in the ambient temperature results in the thermostats calling for a supply of fuel which is sufficiently large to be readily ignited. The valve mechanism therefore opens to permit such a relatively large flow of fuel and in so doing reestablishes the supply of auxiliary heat. The thermostat therefore reduces its demand for fuel although the ambient temperature which it is controlling does not change and, in this manner, the supply of fuel is reduced to the actual demand according to the actual ambient temperature.

The invention will hereinafter be described in conjunction with a modulating type of valve in which the valve mechanism is operable to establish a large number of varying supplies of fuel to the burner, but it should be understood that the invention is also applicable to other types of control systems in which the valve mechanism is only operated in steps to a relatively small number of fuel supply controlling positions.

Other objects of the invention will be found in the drawing, the detailed description, and in the appended claims.

For a more complete understanding of the invention, reference may be had to the following description and the accompanying single drawing which is a diagrammatic representation of 1 the preferred form of the present invention.

Referring to the drawing, the valve mechanism is herein illustrated as comprising a single valve the partition wall of which is indicated at I6. The partition wall I6 is provided with the usual valve opening H which is adapted to be closed off by a valve disc l2. The valve disc I2 is normally biased towards closed position by a coiled spring l3 one end of which abuts the valve disc I2 and the other end of which abuts a flanged base plate I4. The valve disc I2 is secured to one end of a valve stem |5 which extends through an opening |6 formed in the base plate l4 and has its other end connected to a yoke member H.

The yoke member I? is pivoted to a lever |8 at a point indicated at I9, the lever in turn being pivoted at a point indicated at 26. Pivoted to the lever 26 at some point such as is indicated at 2|, is a link 22 which is provided with a hooked end indicated at 23. The hooked end 23 of the link 22 is adapted to be engaged by a crank pin 24 carried by a main operating gear 25 that is secured to a main operating shaft 26. This main operating gear 25 is connected to a motor pinion 21 through suitable gear reduction generally indicated at 28. The motor pinion 21 is secured to a rotor shaft 28 which has a rotor 29 afiixed thereto. The rotor 29 comprises a portion of a motor generally indicated at 36 which additionally includes a pair of field windings 3| and 32 each of which, when energized, is adapted to impart force to the rotor 29 tending to rotate the same in a counter-clockwise direction as viewed from the left in the drawing.

Secured to the shaft 26 is an actuator 35 which, upon clockwise rotation of main operating shaft 26, is adapted to engage an assembly 36. When the assembly 36 is moved to its uppermost position corresponding to a wide open position of the valve, it is adapted to engage the extended end of a contact arm 31 and move its contact 38 from engagement with a cooperating contact 39 carried by a similar shorter contact arm 46. Similarly, upon extreme downward motion of assembly 36 corresponding to a closed position of the valve, the assembly 36 is adapted to engage the extended end of a contact arm 4| thereby to move its contact 42 from engagement with a cooperating contact 43 carried by ashorter contact arm 44. The switches comprised by contacts 38-39 and 42-43 are in the nature of limit switches as will hereinafter become apparent. The assembly 36 also includes a contact finger 45 which is adapted to move up and down upon a resistance element 46 coiled upon a suitable support indicated at 41.

An adjustable bracket 56 includes a contact arm 5| which is adapted to engage the rear surface of resistance element 46 at a point depending upon the adjustment of bracket 56. A second adjustable bracket 52 is provided with a cam surface 53 upon which the contact finger 45 is adapted to ride during downward movement of assembly 36 whereby the contact finger 45 is lifted' from engagement with the resistance element 46.

The motor 36 is controlled by a relay generally indicated at 66 which comprises a pair of relay windings 6| and 62 having a junction as indicated at 63 and. adapted to exert opposing magnetic forces upon a plunger 64. The plunger 64 is connected to a switch arm 65 by means of a coiled spring 66 and a non-magnetic connecting member 61. This switch arm 65 and a flexible switch arm 68 are secured to a bracket 69 which is pivotally mounted at a point indicated at 16. The flexible switch arm 68 carries a contact II which cooperates with a stationary contact 12, whereas the switch arm 65 carries a contact I3 which cooperates with a stationary contact M.

The condition responsive controller is herein shown in the form of a potentiometer room thermostat generally indicated at 15. This potentiometer room thermostat includes a temperature responsive element 16, herein shown in the form of a coiled bimetallic element, having one of its ends fixed as indicated at T1 and its movable end carrying a control member in the form of a contact arm 18. The contact arm 18 engages a control resistance 19 and is adapted to sweep back and forth thereacross upon changes in the temperature to which the bimetallic element 16 responds.

Low voltage electrical power is supplied by a step-down transformer 86 which is provided with a low voltage secondary 8| and a high voltage primary 82 which is connected to suitable line wires indicated at 83 and 84. The free ends of relay windings 6| and 62 are connected to the secondary 8| by wires 85, 86, 81, and 88 so that the relay windings 6| and 62, in series, are connected across secondary 8|. The free end of relay winding 6| is also connected to the upper end of the resistance element 46 (which acts as a balancing resistance as will hereinafter become apparent) and to the right-hand end of control resistance 19, through a protective resistance 89, by means of wires 96 and 9|. Similarly, the free end of relay coil 62 is also connected to the lower end of resistance element 46 and to the left-hand end of control resistance 19, through a protective resistance 92, by means of wires 93, 94, and 95. The junction 63 of relay windings 6| and 62 is connected to the contact finger 45 and to the contact arm 18 by means of wires 96, 91, and 98. Contact finger 5| of bracket 56 is connected to bracket 52 by a wire I36.

One end of each of the field windings 3| and 32 is connected to one side of secondary 8| by means of wires 88, 99, I66, |6|, and I62. The other end of field winding 3| is connected to contact 43 by a wire I63 and is also connected to the other side of secondary 8| through a switch |64 by wires I65, I66, I25, and 85. Similarly, the other end of field winding 32 is connected to switch arm 46 by a wire I61 and is also connected to the other side of secondary 8|, through a switch I68, by means of wires I69, I66, I25, and 85. The switch arm 4| is connected to contact 12 by a wire ||6, and the switch arm 31 is connected to contact 14 by ai'wire III. The switch arms 65 and 68 are connected to a small number of turns of relay winding 6| by means of a wire 2.

The apparatus thus far described is not new with the present inventor and is disclosed in detail and claimed in the copending application of Lewis L. Cunningham, Ser. No. 697,686, filed November 11th, 1933,'and entitled Modulating electric valve. This valve mechanism as thus far described operates to remain closed until there is a demand for fuel corresponding to a relatively wide open position of the valve depending upon the position of contact finger 5| in relation to the resistance element 45. The valve mechanism after having been opened to this relatively wide'position thereafter modulates or proportions the flow of fuel in accordance with the position of the control member I8 upon control resistance I9 until such time as the valve reaches a nearly closed position whereupon it quickly closes, the cut-off position depending upon the position of cam member 53, all-as will be described in more particularity in connection with the present invention.

In order to carry out the objects of the present invention, the response of the condition responsivecontroller I5 is varied or changed under certain conditions. This is preferably accomplished by providing an electric heater H5 which is adapted to furnish a small amount of local heat to the bimetallic element I6. This electric heater H5 is controlled by a switch comprising switch arms H6 and II! which are secured to the base I4 through suitable insulating blocks H8 and H8. The switch arm H6 carries a contact I20 which is biased to engage a similar contact |2| carried by the switch arm I". The switch arm I I1 is provided with an extended end which lies in the path of downward movement of yoke I1 and is adapted to be engaged by the yoke I! when the valve disc I2 moves to a position closing off the fiow of fuel through the valve opening H. For all other positions of yoke II, the contacts I20 and |2I are closed. The electric heater H5 is connected to the secondary 8| through the switch comprised by contacts I20 and|2| by means of wires 85, I25, I25, I21, I28, 89, and 88.

Operation Assuming that the condition responsive controller I5 responds to the temperature of the space to be heated, the arrangement is preferably such that movable member I8 engages the cold or right-hand end of control resistance I9 when the temperature at the bimetallic element I6 is 70 F. and engages the hot or left-hand end of control resistance I9 when the temperature at bimetallic element I5 is 72% F. The electric heating element H5 'is so proportioned as to raise the temperature of bimetallic element 16 one-half degree above the ambient or space temperature. As a result, whenever the heating element H5 is energized, the control member I8 will move from the cold end of control resistance I9 to the hot end thereof upon ambient or space temperature variations of from 70 F. to 72 F., the extra half degree of heat required at the bimetallic element I6 being furnished by the heating element I I5. This is the normal operating response of the condition responsivedevice 15, and it will be noted that this normal response is made up of two factors, one being the ambient or space temperature which it is desired to control and the other being the predetermined amount of heat transmitted to the bimetallic element I6 by the electric heating element H5. It will be understood that the heating element H5 is closely associated with the bimetallic element I6, and that the amount of heat which it gives oif, while being sufilcient to raise the temperature of the bimetallic element I6 one-half degree, has no measurable elfect upon the ambient or space temperature.

With the parts in the position shown, the adjustable contact arm 5| is engaging approximately the center of balancing resistance 46 and likewise the contact finger 4 5 is also engaging approximately the center thereof. The switch defined by contacts I28|2| is closed so that heating element H5 is energized. The control member I8 is engaging the center of control resistance I8 thereby indicating that the ambient temperature is 71 F., although the temperature at bimetallic element I6 is, in fact, 71 F. by reason of the auxiliary heat furnished by the heating element H5. The valve mechanism is half-open and the relay coils GI and 62 are substantially equally energized, the difference in energization resulting from the fiow of current through the small number of turns of relay winding 8| as will hereinafter become apparent. It should be noted at this time, that the contacts H and I2 are engaged whenever the relay winding 6| is energized to the same extent as or slightly greater than the relay winding 82. Motor field winding 3| is energized by a circuit as follows: secondary 8|, wire 85, wire 86, the small number of turns of relay winding 8|, wire I I2, switch arm 68, contacts 1| and I2, wire H8, contacts 42 and 43, wire I03, field winding 3|, wire |8|, wire I88, wire 88, and wire 88 to the other side of secondary 8|. The force or torque produced by this single field winding 3| taken together with the friction of the parts is sufficient to hold the valve disc I2 in any position to which it is moved against the biasing force of spring l3 so that the valve disc I2 remains in its halfopen position. Now, if the room temperature should rise somewhat, causing control member I8 to move along control resistance I9 towards the left-hand end thereof, the voltage drop across relay winding 6| will be increased and the voltage drop across relay winding 82 will be decreased whereupon plunger 64 will move to the left and bring contact I3 into engagement with contact I4. Field winding 32 will thereupon be energized as follows: secondary 8|, wire 85, wire 86, the small number of turns of relay winding 6|, wire H2, switch arm 65, contacts I3, and I4, wire HI, contacts 38 and 38, wire I01, field winding 32, wire I02, wire I00, wire 98, and wire 88 to the other side of secondary 8|. This additional fiow of current through the small number of turns of relay winding 6 I slightly increases its pull upon plunger 54 so as to move contact I3 more firmly intoengagement with contact I4 and eliminates any possibility of contact chatter. Energization of field winding 32 supplies an additional force or torque to rotor 29 which is suflicient to cause rotation of main gear 25 and actuator 35 in a clockwise direction. The valve I2 is thereby lifted to a more wide-open position, and the contact arm 45 simultaneously moves upwardly along balancing resistance 48. These movements continue until the contact finger 45 reaches a point upon balancing resistance 46 such that the voltage drops across relay windings SI and 62 are again substantially equalized whereupon plunger 84 moves back to the position shown in the drawing and contact I3 disengages contact I4. Contact I I, however, remains in engagement with contact I2 so that while field winding 32 is deenergized, the field winding 3| remains energized and its force or torque taken in conhection with the friction of the parts causes the valve disc I 2 to be maintained in the new position to which it has been moved. If the space temperature rises to 72 F., the control member 18 will engage the extreme left-hand end of control resistance I9 and substantially short-circuit the relay winding 62, contacts 13 and I4 will again be closed and field winding 32 again energized. The main gear 25 and actuator 35 will therefore be rotated in clockwise direction until the valve is completely opened and the contact finger 45 engages the extreme upper limit of balancing resistance 46 at which time the relay winding 6| is substantially short-circuited and the plunger 64 returns to the position shown in the drawing. The protective resistances 89 and 92 prevent the complete short-circuiting of relay windings GI and B2 and thereby cause the same to always receive at least a predetermined minimum amount of current so that they remain operative to control the plunger 63. Movement of assembly 36 to this extreme upper position opens contacts 38' and 39 and deenergizes field winding 32 so as to reduce the current flow to the motor 30 when the valve has-been completely opened.

Whenever the temperature falls so as tomove control member i8 along control resistance E9 towards the right-hand end, the voltage drop across relay winding 62 will be increased and the voltage drop across relay winding 6! will be decreased, whereupon plunger 66 will move sufiiciently to the right to move contact ll from engagement with contact 72. Field winding 36 is thereupon deenergized, as well as field winding 32, and the spring 63 moves the main gear 25 and actuator 35 in counter-clockwise direction and moves the valve disc l2 towards closed position. The contact finger d therefore moves downwardly along balancing resistance :36 until such time as the voltage drops across relay windings 6i and 62 are again made substantially equal, whereupon the plunger, 6d moves to the position shown in the drawing wherein contact if engages contact i2. Field winding 3! is thereupon energized by the circuit heretofore described and prevents further closing movement of valve disc l2. In this manner. the valve disc 52 is modulated between its limits of movement in accordance with the position of control member 78 upon the control resistance l9. .When the space temperature rises to approximately 71 F., control member it will engage the control resistance H9 at a point intermediate its left or hot end and its center portion. The valve will therefore move to its quarter-open position at which point the contact finger 45 rides up the cam surface 53 and out of engagement with balancing resistance it so that the voltage drops across relay windings 6i and 62 cannot be equalized. Contacts ii and i2 therefore remain open, and the valve will move to its full closed position. In this manner, the valve can only be modulated to some minimum flow position depending upon the adjustment of cam member 53, whereupon the valve quickly moves to full closed position. When this occurs, the switch defined by contacts I and IN is opened and the heating element H5 is deenergized.

The temperatureat bimetallic element i6 is therefore immediately reduced /f F. although the. ambient or space temperature remains the same. This /2" F. temperature fall at bimetallic element 16 causes the movable member 78 to move towards the cold or right-handend of con-' trol resistance 19 and assume a position substantially at.the center thereof. By reason of the fact that contact finger 45 isengaging cam member 53, which in turn is connected to contact finger 5| by the wire I30, and since the contact finger 5| is engaging the balancing resistance 56 just above its central portion, the voltage drop across relay winding 6| can only become greater I presented by the ambient temperature.

aosasee than the voltage drop across relay coil 62 when the control member 73 moves past the center of control resistance 79 and towards the cold end thereof. Because the heating element H5 has been deenergized, however, the control member 18 immediately moves to substantially the center portion of control resistance 19 without any change in the ambient or space temperature. It results, therefore, that a relatively small decrease in the ambient or space temperature will cause control member F3 to move past the center of control resistance 79 and towards. the cold end thereof, whereupon the voltage drop across relay winding Si will become greater than the voltage drop across relay winding 52 and contact it will move into engagement with contact i2 and contact 13 will move into engagement with contact it. Engagement of contact ill with contact "i2 is inoperative to energize field winding 3i since, during the closing movement of the valve, the 'main gear and actuator 35 coasted past the valves closed position by reason of their mojmentum, such coasting being allowed by the oneway connection provided by crank pin Maud the hooked link 22; and thismovement of actuator 35 allowed the assembly 35 to open the limit switch defined by contacts 52 and 53. Engagement of contact l3 with contact 7H3, however, causes energization of field winding 32 by the circuit heretofore described, whereupon the rotor 29 causes rotation of main gear 25 and actuator 35 in a clockwise direction. This lost motion is first taken up, and during this period the assembly 36 rises a small amount and allows contacts t2 and 83 to close, whereupon field winding 3i is'also energized. The full power of the motor 38 is now available and the crank pin i l moves into engagement with the hooked link 22 and raises the valve disc i2 against the bias of spring 63. Contact finger 55 will therefore move upwardly along cam 53 and then onto and upwardly along balancing resistance it but will be unable to rebalance the relay windings 6i and 62 until it passes beyond the point at which contact finger 59 engages the balancing resistance t6. In this manner, the valve is initially moved to half-open position or perhaps a little more widely than this and, during such movement, the switch defined by contacts H28 and iii recloses. A large supply of fuel is thereby initially provided for the burner which supply of fuel z-is readily ignited. The heating element H5 being again energized begins to transmit heat to the bimetallic element l6 and will soon raise the same one-half degree above the ambient temperature, whereupon control member it will move almost to that position requiring only a quater-open valve position. The valve will therefore move to about quarter-open position to reduce the supply of fuel to the burner to correspond to the demand Thereafter, the valve is free to be modulated up or down in the manner heretofore described in accordance with changes in the ambient temperature.

In this manner, by changing the adjustment of thecondition responsive controller eachtime the supply of fuel is discontinued and each time the supply of fuel is initially established, it is possible to create a false demand for fuel while the porary opening of the valve in order to establish resulting in a relatively wide momentary or temas soon as the valve has been opened, thereby valve is closed and to rectify this false demand proper ignition upon a considerably smaller deaosasee mand for fuel than that which corresponds to such relatively wide-open position of the valve. It will be appreciated that the condition responsive control need not be responsive to a temperature condition, and it will further be readily apparent that means other than the use of auxiliary heat could be utilized for causing this false demand for fuel whenever the valve mechanism moves to closed position. Further, the invention is applicable to valve mechanisms having a relatively small number of open positions. Many other changes in the specific embodiment herein set forth can readily be made by those skilled in the art, and I therefore intend to be limited only by the scope of the appended claims.

I'he switches ltd and W8 are adapted to be manually closed by an operator itl in the usual manner and latched closed after the manual opening of the valve by means of lever is in the event of a power iailure in order to provide an automatic recycle of the apparatus upon the resumption of power in a manner well-known in the art and fully described in the Lewis L. Cunningham application referred to hereinbefore.

I claim:

1. In combination, valve means for controlling the flow of fuel to a burner, a temperature responsive controller for operating said valve means to at least two difierent open positions upon con tinued decrease in the temperature to which said controller responds, auxiliary heating means for locally efiecting the response of said temperature controller, and means controlled by said valve means when in closed position for rendering said auxiliary heating means inoperative, said auxiliary heating means being of insufilcient capacity to raise the temperature at said controller sufficiently to cause closure of said valve when the ambient temperature is of such value that it alone would cause opening of said valve to an open position greater than its minimum open position.

2. In combination, valve means for controlling the flow of fuel to a 'burner, a temperature responsive controller for operating said valve means to at least two difienent open positions upon continued decrease in the temperature to which said controller responds, an electrical heating element for locally heating said temperature responsive controller, a-switch in control of the flow of electrical power to said heating element, and connections between said valve means and switch for moving the same to a position to operatively deenergize said electrical heater upon closure of said valve means, the heating efiect of said heating element upon said controller being insufficient, when the ambient temperature alone is such as to demand, opening of said valve means to a greater extent than its minimum open position, to cause complete closure of said valve means upon energization of said heating element.

3. In a temperature control system for heating.

a space, in combination, valve means in control of the fiow of fuel to a burner for heating said to open circuit position upon closure of said valve means, said electrical heating element having only sumcient efiect upon said controller to cause moving said valve means to at least one smaller open position before closing the same upon tem perature rise, means for changing the response of said temperature controller so that the same assumes a position requiring said relatively large valve means opening before said temperature condition is such as to require said large valve means opening whereby said valve means are initially operated to said large open position upon a relatively small temperature fall, and means operated by said valve means in moving to closed position for operating said temperature controller response changing means to cause said temperature controller to require said smaller valve means open position. I

5. In combination, valve means for controlling the flow of fuel to a burner, a temperature responsive controller responsive to a condition to be controlled associated with said valve means for initially opening said valve means to permit a large flow of fuel to said burner when said controller is in a first position, to permit a lesser how of fuel to said burner when said controller is in a second position, and to permit no flow when said controller is in a third position, and means associated with said controller for causing the same to assume said first position before the temperature to be controlled is such as to require the controller to be in said first position, and means controlled by said valve means when in closed position for operating said means.

6. The combination with a temperature responsive controller for initially opening a valve means to a relatively wide open position at a first temperature value and for moving said valve means to an intermediate open position at a second higher temperature value before closing the same at a third still higher temperature value, of means for artificially changing the response of said temperature controller whereby the same opens said valve to said relatively wide-open position before the temperature to which it responds falls to said first value, and connections between said means and said valve means for operating said means upon closure of said valve means.

7, In combination, a temperature responsive controller, an electrical heating element for local-' 1y heating the same whereby said controller responds to a combination of the ambient temperature and said local heat, valve means initially moved to a relatively wide-open position when the temperature at said controller falls to a predetermined value and moved'to an intermediate open position when the temperature at said controller is partially restored, and switch means operated by said valve means when moved to closed position for deenergizing said heating element whereby the temperature at said controller is reduced to cause said controller to open said valve means to said relatively wide-open position upon a relatively small decrease in the ambient temperature, the heating effect of said heating element being only sufficient to cause said controller to move the valve means to its intermediate open position when the ambient temperature alone is such as to require the controller to move the valve means to its relatively wide-open position.

8. The combination with valve means and a temperature responsive controller for initially opening said valve means to a relatively wide position upon temperature fall and for moving said valve means to an intermediate open position prior to closing the same upon temperature rise, of an actuator associated with said temperature responsive controller and controlled by said valve means for changing the response of said controller to the temperature to be controlled when said valve means is in closed position in such manner that a relatively small fall in the temperature to be controlled is required to cause said controller to move said valve means to said relatively wide-open position whereupon the response of said controller is again changed to cause said valve means to assume said intermediate position without any further change in the temperature to which said controller responds.

9. The combination with valve means and a temperature responsive controller for initially opening said valve means to a relatively wide position upon temperature fall and for moving said valve means to an intermediate open position prior to closing the same upon temperature rise, of an electrical heating element for locally heating said controller a predetermined amount when energized, and a switch controlled by said valve means and moved thereby to a position in which said electrical heating element is operatively deenergized upon closure of said valve means whereby upon closure of said valve means the extra supply of heat is removed from said controller so that the same requires opening of said valve means to said relatively wide-open position upon a small decrease in temperature and is thereupon locally heated sufi'iciently to cause a partial closing of said valve means. i

10. The combination with valve means for controlling the flow of gas to a burner and a controller responsive to a heat condition adapted to open initially said valve means to a relatively wide position when said controller reaches a first position, to move said valve means .to an intermediate open position when said controller reaches a second position, and to close said valve means when said controller reaches a third position, of.

an actuator associated with said controller and operated upon opening of said valve means, said actuator operating to move said controller from said first position to said second position without any change in the condition to which it responds whereby a large supply of gas is initially furnished to said burner for ignition purposes and automatically reduced to the desired flow.

11. The combination with valve means for con-.

trolling the flow of gas to a burner and a controller responsive to a heat condition adapted to open initiallysaid valve means to a relatively wide position when said controller reaches a first position, to move said valve means to an inter- I mediate open position when said controller reaches a second position, and to close said valve means when said controller reaches a third position, of an electrical heater forlocally heating.

said actuator an amount to move the same from said first position to said second position without any change in the heat condition to which said controller responds, and'a switch rendered operative to operatively energize said electrical heater upon opening of saidvalve ineans whereby, upon movement of said controller to said first position to supply initially a large flow of gas to the burner for ignition purposes, said valve means is automatically returned to an intermediate position.

12. The combination with valve means for modulating the flow of gas to a burner and a controller responsive to a heat condition for modulating said valve means in accordance with changes in said heat condition wherein the arrangement is such that said valve means is maintained closed until said controller reaches a position demanding a relatively large fiow of gas and is thereafter modulated towards closed position as the heat condition requires such modulation, of an actuator associated with said controller and rendered operative upon opening of said valve means for automatically moving said controller from said position demanding a relatively large fiow of gas to a position requiring a lesser fiow of gas whereby a large fiow of gas is initially supplied to the burner for ignition purposes and is thereafter reduced to the desired amount.

13. A system of the class described, comprising, in combination, normally closed valve means in control of the fiow of fuel to a burner, a main controller responsive to a condition for operating said valve means to at least two fiow controlling positions other than the position in which no flow is permitted and for maintaining the valve means in such positions, as the condition to which said controller responds changes in one direction, and means controlled by said valve means for changing the response of said controller when said valve means is in no flow position in such manner that said controller responds to said condition at values other than the desired values whereby a false indication of a demand to open said valve means is obtained when said valve means is in no flow position.

14. A system of the class described, comprising, in combination, valve means normally biased to closed position for controlling the fiow of fuel to a burner, a main controller responsive to a condition for operating said valve means to at least two different open positions upon changes in the value of said condition in one direction and for maintaining the valve means in such positions as long as such values of the condition persist, means for locally affecting said condition responsive controller to change the response of the same so that the response of the controller to the combined action of the condition and such local means is the desired response of such controller, and means controlled by said valve means when in closed position for rendering said local means inoperative to affect said controller whereby said controller gives a false demand for opening ofsaid valve means when the valve means is in closed position.

15. In combination, valve means for controlling the fiow of fuel to a burner, a temperature responsive controller for operating said valve means to at least two difierent open positions upon continued decrease in the temperature to which said controller responds from normal, electrical means associated with said temperature responsive controller for locally heating the same to change its response to the prevailing temperature condition to which it primarily responds and in such manner that the desired response is obtained when the controller is so locally heated, and circuit controlling means for controlling said electrical means moved to a new circuit controlling position upon closing of said valve means to operatively deenergize said electrical means, 76

whereby a false demand for opening said valve means is obtained when the valve means is in closed position.

16. In a control system, in'combination, a variably positionable controlling device, a condition responsive controller, means controlled thereby to variably position said controlling device in a plurality of intermediate positions upon fluctuations in the condition to which said controller responds, and means to change the response of said controller in a manner to cause a partial movement of said controlling device without any change in the value of the controlling condition, said response changing means being placed in operation upon movement of said controlling device out of one of its extreme positions.

17. In a temperature control system, a temperature changing device, a modulating power means to variably position the same, a controller responsive to the temperature of a medium in 'control of said power means operable to position the same in accordance with the variations in such temperature, and auxiliary temperature changing means to locally afiect said controller to cause movement of said power means through only a portion of its range placed in operation upon movement of said power means out of one of its extreme positions.

18. In a control system, in combination, a device for controlling a condition, a condition responsive controller in control of said controlling device, means normally locally afiecting said condition responsive controller in such manner that the combined response of the condition responsive controller to the medium to which it is exposed and to said local means gives the desired control action, and means operative to render said local means inoperative when said controlling device is moved to an extreme position whereby a false demand for movementof said controlling device is obtained whenever the controlling device moves to such an extreme position.

GEORGE H. FISHER. 

